Solatube sun pipe tube lengths - the long and the short of it
We’re often asked ‘can you fit a really short Solatube straight through a flat roof?’ (Yes!). And we’re also asked ‘what’s the longest tube run you can have with a Solatube sun tunnel?’ (Longer than you’ll ever need – from 6m upwards!). So I’ve decided to explain all this in the blog below:
Solatube sun tunnel in a flat roof? No problem!
The good news is that Solatube sun tunnels can be easily fitted straight through a flat roof. In fact the shorter the tube run, the better. And whatever the roof covering, be it felt, fibreglass or single ply (rubber) membrane, a Solartube sun pipe can be fitted in almost any type of roof covering. With a range of Solatube roof flashings we can ensure your Solatube will be weathered in to prevent any leaks whatsoever.
Contrary to what many people believe, a Solartube sun pipe does NOT need a minimum tube length in order to work. Therefore it is possible to install a Solatube in any thickness of roof – we even install them in wooden sheds and garden studios and offices.
How long can a Solatube be? Very long…!
Once again, you just don’t need to worry. Even the smallest 25cm dia Solatube 160DS can deliver significant amounts of daylight down 6m / 20’ of tube length – that’s more than the height of 2 rooms and up to gutter height of most 2 storey houses. In fact it’s rare for any residential Solatube sun tunnel installation to be more than 4m and the most common Solatube installation tube length tends to be up to around 1.5m / 5’.
What light loss is there with sun pipes?
This all depends on how reflective the tube is and each type of system uses different levels of reflectivity. Fortunately, Spectralight® Infinity Tubing used in Solatube sun tunnel systems is made of the world’s most reflective material. Used inside a Solatube it ensures the maximum amount of light that enters the Solatube at the top can be reflected, or bounced, down the tube into the room below.
Other systems use less reflective material, frequently 98% reflective. Now this may not sound very different from 99.7% reflective, but let me assure you, it makes a very big difference and I’ll explain why.
Each time light bounces or reflects off a surface inside a Solatube with 99.7% reflective material it loses just 0.3% of its energy, or its light. Whereas with 98% reflective material, each time light bounces it loses 2% of its light. Now multiply this up over a number of bounces that light has to make to get down a tube, and we’ll keep this simple and base it on 10 bounces (but it could be 20 or 50 or 100…). The 98% reflective tube loses a whopping 20% of the light as it travels down the tube.
The Solatube on the other hand, with 99.7% reflectivity, loses just 3% of the light. And this is one of the main reasons why Solatube sun tunnels are the brightest systems in the world, delivering more light than almost every other solution.
So, as I’ve mentioned before, the longer the tube run, the less light; and the more angles and bends the less light. Or put another way, the shorter and most direct the tube run usually gives you the most light. However, thanks to the highly reflective tube used in the Solatube, as a rule of thumb we work on losing perhaps 5% of the light for every full 3m of tube length and similarly around 5% for a full 90* elbow or bend. And just to be clear, a 5% difference is an extremely small difference and is something that most of us would be unable to detect or pick up.
So, to reiterate…
It doesn’t matter how long or how short you need your sun pipe to be, Solatube sun tunnels can be almost any length. You can easily fit a Solatube straight through a flat roof with next to no tubing; you can also install a Solatube from your roof, down through the room below and even another room below that and still deliver extremely bright daylight. Just make sure you use a Solatube otherwise you might find yourself in the dark!